For even the most committed coward, there comes a time when a nagging terror
can no longer be ignored.

Whether it’s finally having the doctor look at that itchy, raised mole, or opening the Inland Revenue brown envelope that has lain menacingly unopened on the sideboard for months, the potentially hideous truths must eventually be faced.

Until his US Open defeat to Stanislas Wawrinka, those of us who crave a grand slam title for the Scot have suppressed the fear that, for all his technical brilliance, he may not have it in him.

So often has Murray departed majors after an opponent produced the tennis of his career, as with eventual finalist Jo-Wilfried Tsonga in the first round of the 2008 Australian Open, that his failure to win one could be dismissed as a transient jinx.

The defeat to Wawrinka, however well the Swiss No 2 and his exquisite one-handed backhand performed, was something different. Here was a study in mental frailty to make Tim Henman at his most enfeebled look like Rafael Nadal at his most ferociously defiant.

However painful the vision of Murray’s disintegration after failing to hold serve for a two-set lead, the ensuing press conference was more so.

Utterly forlorn, dejected and bemused, he could offer no reason for the sudden and total drainage of energy that brought to mind a plane sent into a corkscrew spin by the loss of all its engines.

The explanation seemed purely psychosomatic. The power of neurosis to produce more tangible physical symptoms than fatigue is, as all decent hypochondriacs will know, astounding.

Soon after convincing myself once that I was in the latter stages of heart failure, a watery swelling (oedema) appeared on my right ankle.

A year later, after a thorough examination, the GP declared that the only specialist to whom she would refer me was a psychiatrist. The next morning, the swelling had vanished.

On Sunday, it was heart failure of another kind that both preceded and provoked Murray’s exhaustion. After edging the first set Murray’s courage deserted him, and that fatal penchant for awaiting unforced errors rather than imposing himself re-exerted itself.

In this, he is the equivalent of the England football team attempting to husband a 1-0 lead by defending too deep in defiance of their own will and their coach’s express instructions.

The only rival whom Murray always relentlessly attacks, liberated by the certainty that he cannot outlast the Spaniard in rallies, is Nadal.

Extending that fearless aggression to other opponents is a challenge that may, being middle aged in tennis terms at 23, be beyond him.

Following the Wawrinka disaster, there is talk of him needing a new coach, and one less matey and indulgent and more disciplinarian than the entourage presently led by his mother Judy.

Close comparison of England’s World Cup form under Sven-Goran Eriksson and Fabio Capello respectively warns against too much faith in that particular fix.

Some flaws are too deeply buried for even the finest coach to reach, and it begins to look like Murray’s is the familiar one of being British.

Like Paula Radcliffe, so dominant in the marathon until drained by the stress of Olympic favouritism, and compatriot Colin Montgomerie, who won countless minor tournaments but collapsed when poised to win a US Open, perhaps he cannot bear the weight of expectation this country imposes on its sporting stars even when he is not consciously aware of it.

Tennis, like psychosomatic exhaustion, is a game of the subconscious mind.

So if he must have a new coach, my suggestion would be Paul McKenna, whom boxer Nigel Benn thanked for the bewildering reserves of energy that somehow took him to victory over Gerald McClellan in that peerlessly brutal and ultimately tragic world title fight.

If McKenna could hypnotise Murray to believe he is German or Australian, and always to see Nadal on the other side of the net, he would confirm himself as the world’s preeminent hard court player at US and Australian Opens, as he does in the Masters series events he routinely wins with the capacious self-belief that evaporated so alarmingly in New York this week.